Role of endothelial cell autoantibodies in the pathogenesis of sudden hear loss

Sudden hearing loss can be found in systemic autoimmune diseases or it can be a symptom of an autoimmune disease of the inner ear. The present work has studied a group of patients with idiopathic sudden hearing loss to determine what role anti-endothelial cell antibodies (AECA) play as markers of immuno-mediated vasculitis of the inner ear. The study involved 32 patients with sudden deafness and 14 controls. The patients underwent otofunctional, neuroradiological, sero-microbiological and immunological testing. Using the indirect immunofluorescence technique, serum AECA were determined within 24 hours of hospitalization and three days after the onset of deafness. AECA positive patients (AECA+) were administered corticosteroid therapy (methylprednisone 1 mg/kg/die) for 1 month. A clinical follow-up was performed, including audiometry, 1 month after discharge and thereafter at three-month intervals (follow-up range: 8-18 months). AECA proved positive in 15/32 patients (47%) and in 2/14 of the controls (14%). The difference between the patients and the controls was statistically significant (p = 0.03). The 7 patient who showed no recovery after 1 month were all AECA+. None of the AECA+ patients showed other symptoms or a worsening of the hearing loss. In conclusion, the determination of non-specific autoantibodies vs. the inner ear, such as AECA, can be considered a useful clinical tool in differentiating between patients with idiopathic sudden hearing loss and those for which a diagnosis of immuno-mediated vasculitis of the inner ear is likely and for which prognosis is particularly unfavorable.